• ETRI Journal
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• v.21 no.4
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• pp.52-64
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• 1999

QoS monitoring is a kind of real-time systems which allows each level of the system to track the ongoing QoS levels achieved by the lower network layers. For these systems, real-time communications between corresponding transport protocol objects is essential for their correct behavior. When two or more entities are employed to perform a certain task as in the case of communication protocols, the capability to do so is called interoperability and considered as the essential aspect of correctness of communication systems. This paper describes a formal approach on modeling and interoperability test case generation of a real-time QoS monitoring protocol. For this, we specify the behavior of flow monitoring of transport layer QoS protocol, i.e., METS protocol, which is proposed to address QoS from an end-to-end's point of view, based on QoS architecture model which includes ATM net work in lower layers. We use a real-time Input/Output finite State Machine to model the behavior of real-time flow monitoring over time. From the modeled real-time I/OFSM, we generate interoperability test cases to check the correctness of METS protocol's flow monitoring behaviors for two end systems. A new approach to efficient interoperability testing is described and the method of interoperability test cases generation is shown with the example of METS protocol's flow monitoring. The current TTCN is not appropriate for testing real-time and multimedia systems. Because test events in TTCN are for message-based system and not for stream-based systems, the real-time in TTCN can only be approximated. This paper also proposes the notation of real-time Abstract Test Suite by means of real-time extension of TTCN. This approach gives the advantages that only a few syntactical changes are necessary, and TTCN and real-time TTCN are compatible. This formal approach on interoperability testing can be applied to the real-time protocols related to IMT-2000, B-ISDN and real-time systems.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.691-694
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• 2003

This paper describes how to use Profibus networks to support real-time industrial communications, that is, how to ensure the transmission of real-time messages within a maximum bound time. Profibus is based on a simplified timed token protocol, which is a well-proved solution for the real-time communication systems. However, Profibus differs from the timed token protocol, thus the usual timed token protocol has to be modified in order to be applied in Profibus. In fact, the real-time solutions for networks based on the timed token protocol rely on the possibility of allocating specific bandwidth for the real-time traffic. This means that a minimum amount of time to transmit the real-time messages is always guaranteed whenever each token is arrived. In other words, with the Profibus protocol, at least, one real-time message should be transmitted per every token visit in the worst case. It is required to control medium access properly to satisfy the message deadlines. In this paper, we have presented how to obtain the optimal network parameter for the Profibus protocol. The selected network parameter is valid regardless of the behavior of asynchronous messages.

• Journal of Institute of Control, Robotics and Systems
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• v.13 no.6
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• pp.596-602
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• 2007

Recently, many ECUs(Electronic Control Units) have been used to enhance the vehicle safety, which leads to a distributed real-time control system. The distributed real-time control system requires to reduce the network delay for dependable real-time performance. There are two different paradigms by which a network protocol operates: event-triggered and time-triggered. This paper focuses on implementation of a time-triggered protocol. i.e. TTP/C(Time-Triggered Protocol/class C). This paper presents a design method of TTP control network and performance evaluation of distributed real-time control system using TTP protocol.

• The Journal of the Korea Contents Association
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• v.8 no.2
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• pp.57-66
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• 2008

Most concurrency control protocols have been devised for resolving data conflicts among real-time transactions of a single type. Recent real-time database systems should support various types of real-time transactions due to needs of many different types of applications and steady improvement of hardware. In this paper, we propose integrated concurrency control protocol to resolve data conflicts among hard and soft real-time transactions. Our proposed protocol, based on PCP(Priority Ceiling Protocol) for a hard real-time transactions and MVPR(Multiversion with Precedence Relationship), guarantees that hard real-time transactions meet their deadline, and decreases the deadline miss ratio of soft real-time transactions. We also proved that the proposed protocol guarantees serializable schedules and no deadlocks. The performance of the proposed protocol has been compared with other real-time concurrency protocols.

• International Journal of Internet, Broadcasting and Communication
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• v.8 no.1
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• pp.19-26
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• 2016

In this paper, the existing domestic HVAC systems, devices TCP / IP does not support the most, thereby, not performed remote management, it is necessary to regularly field service, inefficiency and cost bring a burden. This is through a comparison of the IoT-based primary, real-time protocol of what has become a hot topic recently, to be able to control and real-time monitoring through the CCU device in the HVAC system. Compare for this Internet of Things device for real-time monitoring and control of the XMPP, CoAP, MQTT main real-time protocol is used on. Finally, flexibility, light weight, based on MQTT a two-way messaging protocols with reliable message delivery, implements the protocol on the real-time HVAC system in the cloud platform.

• Proceedings of the IEEK Conference
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• 2003.11c
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• pp.157-163
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• 2003

IEEE 802.11a Distributed Coordination Function(DCF) Protocol을 사용하여 Real-Time MultiMedia Data의 전송을 수행할 경우, DCF Protocol의 적합하지 못한 Mechanism에 의하여, Data 전송의 극대화를 이루지 못한다. Retransmission이 반복되는 경우, Binary Slotted Exponential Backoff Mechanism은 거대한 Packet Delay와 Jitter의 원인이 되며 Automatic Repeat Request(ARQ) 방식의 Ack Mechanism은 MultiMedia Data를 전송하기에 적합하지 못하다. 본 논문은 위와 같은 문제점을 해결하기 위하여 Real-Time MultiMedia Data을 주로 전송하는 STA에 따른 Real-Time/Non-Real-Time(RT/NRT) Station(STA)의 구분과 보내고자 하는 Real-Time MultiMedia Data의 Network Traffic Load(The Required Bandwidth)를 고려하여, Modified DCF(mDCF) Protocol의 Modified Backoff(mBackOff), Modified BlockAck(mBlockAck) Mechanism을 제시함으로서, Data 전송의 극대화를 제공하며, 또한 IEEE 802.11a와의 호환성을 제공한다.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.35S no.1
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• pp.1-13
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• 1998

The next generation of wireless network will be problably developed as a mobile communications which will support ATM-based multiMedium traffic. We need to develop an dffective MAC protocol in order to support multimedia traffic having variety of QoS characteristics on wireless neteworks. In this paper, we propose a MAC protocol a MAC protocol where mobile terminals having cells to transmit, request slots to base station through requested slot then the base station analyze parameters from mobile and allocate slots to mobile according to priority. The multimedia slot allocation(MSA) protocol divides multimedias applications into real-time/ variant and non real-time services. Entire slots of the frameare partitioned proportionallyby sizeof bandwidth according to types of services, so that related services can use allocated-slots in priority. The proposed algorithm guarantees real time operation since real-time service share slots allocated for non real-real services. The algorithm whih divides slots of the frame is called as an Algorithm A, otherwise as an Algorithm B. The simulation compares by average delay time and cell loss probability between Algorithm and Algorithm B by increasing number of mobile terminal using the proposed MAC protocol. the simulation result for real-time services shows that average delay time and cell loss probability of Algorithm A is better than those of Algorithm B.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2004.04a
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• pp.43-48
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• 2004

RTP that is proposed supplement of real-time services on internet environment, as Real-time Transport Protocol, is the protocol that for the purpose of sending data of stream type. RTP and RTCP(Real-time Transport Control Protocol) basically work at the same time, RTCP serves with state information of network at present. RTP has important properties of a transport protocol that runs on end-to-end systems and provides demultiplexing. It also offer reliability and protocol-defined flow／congestion control that transport protocol like TCP can not provides. In this paper, we look around concept and construction of Differentiated sen1ice tint run on RTP and by setting parameters of packet transfer method be used CBQ(Class-Based Queuing) for packet transfer on Differentiated service, each service queue controls properly through packet scheduling method, such as WRR(Weighted Round Robin) and PRR(Packet-by-packet Round Robin) all service classes do not experience the starvation and confirm the performance through computer simulation to achieve fairly scheduling.

• Proceedings of the IEEK Conference
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• 2000.06c
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• pp.149-152
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• 2000

In the Internet, multimedia data transfer is hard to guarantee the characteristics of the Real-Time because of the Best-Effort of the nature of IP, then additional mechanism is applied to multimedia application for real-time data. In this paper, we introduce the nature of multimedia and the necessary facility for real-time protocol. We propose protocol layer, which has necessary function above mentioned and offer the end-to-end transfer far real-time data. Also, the proposed protocol perform a next low operation: 1) a required information for QoS control by using Feedback mechanism is obtained from sender, 2) divided a transferred packet by delay and loss priority. 3) recognized the low service models, and 4) decided a bandwidth and QoS according to a network state

• Proceedings of the Korean Information Science Society Conference
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• 2008.06d
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• pp.291-296
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• 2008

Wireless network technologies are becoming more widely used in industrial environment. The industrial communication system requires a real-time delivery of messages. The sensors periodically senses the physical environment and wants to deliver the data in real-time to the sink. This paper proposes a real-time protocol for periodic messages on wireless sensor and actor networks to be used in industrial communications. The proposed protocol delivers the data message using the shortest path from the source and the nearest actor. The protocol considers the energy consumption by reducing the number of broadcast messages during flooding. We have evaluated the performance of the proposed protocol using QualNet simulator. The simulation results show that the data messages have been delivered in real-time and the number of broadcast messages is reduced from 90% to 35% compared the existing protocols.